A frequency synthesizer is a device that synthesizes signals to generate and output a desired signal that is related to a reference signal. A frequency synthesizer may be used in radio communications to generate a carrier signal, in a transmitter/receiver in a wireline or optical communications system, in a microprocessor, or in testing equipment for electric circuits, among other circuits.
In general, a frequency synthesizer includes a phase locked loop to set and maintain the output signal of the frequency synthesizer. A phase locked loop may include components such as a phase detector, one or more charge pumps, one or more loop filters, a feedback clock divider, and a voltage controlled oscillator. These components each bring design challenges to be overcome so that a phase locked loop may minimize undesirable characteristics such as susceptibility to phase noise and reference spurs while maximizing desirable characteristics such as frequency range and bandwidth.
The subject matter claimed herein is not limited to embodiments that solve any disadvantages or that operate only in environments such as those described above. Rather, this background is only provided to illustrate one example technology area where some embodiments described herein may be practiced.